I don't think the connection is the same as the front, therefore what you did there does not matter, it is not the same connection. There are normally fitment instructions in the new blade, did you read them ?

WD40 is terrible to the clear coat of cars, if you get any on it. Do not use it, it is not required and will damage the paint.

Most are something like this

 

be sure to check the length of the new one!!!!!!!!!!!!!!!!!!!!!!!!!
couple of years ago all bosch catalogues had wrong info and they had lenght for previous model of 5008... it is longer and damages top braking light if used....
not sure how it is this year but 2 years ago the only suitable one we had in our country was original one from Peugeot

 

i have the same problem.. did you get a fix to this?

 

This video explains how to replace the rear wiper